You can drastically reduce man hour and material cost when you design houses with efficiency in mind though. It takes significantly less engineering to build a 4-floor building compared to a 40-floor skyscraper, which requires digging large holes, carefully installing a central structure, and the work becomes progressively slower when you are near the top. They are also a huge liability long term due to the complexity of the design, making its present value lower. In a real "free" market, all this would be priced in, but it's likely that the industry is controlled by a small number of well funded groups with strong influence in politics (allowing them to get permits and contracts).